The present invention relates to a method for the production of bright steel from rolled steel wire in which the rolled wire is first passed through a straightening and calibrating device to reduce its diameter, then subjected to a peeling operation in which peripheral surface portions of the wire are removed, whereafter the wire is straightened, or whereafter the wire is cut into portions of predetermined length which are then straightened.
In order to essentially increase the output of installations for the production of bright steel from rolled wire, it has been known for quite some time to reduce the diameter of the hot rolled wire prior to the peeling operation in a straightening and calibrating device. This method step has essential advantages. First of all, it is not necessary to pre-treat the wire, since even hot-rolled steel with sharp bends is perfectly straightened in the straightening and calibrating device, properly calibrated and also partly descaled. An additional advantage is that, by calibrating the wire, the material loss during the subsequent peeling operation can be held to a minimum.
If the bright steel wire has to be produced with a high surface finish and to very close tolerances, then the peeled wire is subsequently drawn through a drawing die and subsequently thereto wound up on a reel or cut into portions of desired lengths. If the wire is, subsequent to the peeling operation, drawn through a drawing die, the thus obtained tolerances and the roundness of the bright steel will be sufficient for most applications.
For the production of conical, respectively double conical, helical springs, wire sections are required which have varying diameters over the length thereof. The production of such wire sections on modern peeling machines causes no difficulties since it is possible to control the peeling knives during their rotation about the wire axis in such a manner that the successive sections of the wire will obtain the desired form. A continuous production of such blanks from rolled wire is therefore possible. The individual blanks are separated from each other after the peeling operation and may be subsequently straightened. The straightening of such conical, respectively double conical, wire sections or rods does not present any great difficulties.
Surprisingly, it has however been ascertained that the roundness of the straightened wire sections or rods is inferior to that before the straightening and is not within the close tolerances which are required by the industry. Tests have confirmed the assumption that the change, respectively the impairment of the diameter tolerance, is caused through internal stresses, assymetrical with respect to the wire axis, which are produced in the wire during the reducing process.